The object of the present invention is a xe2x80x9cDrying tunnel for fruit and vegetablesxe2x80x9d.
The tunnel, preferably arranged with the fruit or vegetables ravelling vertically, works with fresh fruit and vegetables and is designed to eliminate the surface moisture they retain after undergoing the pre-packing operations (washing, polishing).
Drying tunnels are known in the prior art of handling fruit and vegetables to improve their market presentation in which the fruit and vegetables move forward on horizontally arranged roller conveyors, whilst they are rubbed by a mass of hot air forced to flow upstream.
Where airflow and temperature are the same, process efficiency depends on the length of the contact between the mass of gas and the fruit or vegetables and therefore, in conclusion, on the tunnel length.
This constraint is sometimes difficult to satisfy, given the limited plan surface available at handling warehouses.
The invention subject of this Patent is designed to overcome the drawback typical of known horizontal drying tunnels described above.
It is therefore designed as a prismatic rectangular box which is internally divided by parallel equidistant vertical walls into preferably identical compartments with a bucket conveyor travelling successively up and down as a continuous chain, arranged so that the compartments each contain a conveyor sector moving in a direction opposite that in which the adjacent compartment is travelling.
The buckets are elongate and their horizontal axis lies parallel to the compartment walls, their ends each being limited by irregular hexagonal plates, swivel hinge pin sectors being located close to each of their top corners, ideally in line, joined to the respective chains driving the conveyor.
The bottom of the bucket that is to hold the fruit whilst it is conveyed within the tunnel is arranged within the concavity defined by the three bottom corners of the end hexagonal walls, made in such a way as to allow an airflow through it (for instance, spaced longitudinal rods, perforated plate, etc.).
Short shafts are arranged projecting from the bucket at each of the top inner corners of said hexagonal walls, their free ends each provided with bearing means (bearings for instance) which, in the last downward sector of the conveyor, abut against flat symmetrical guides with a downward incline, causing the bucket to swivel upon abutting thereon, thereby for it to be tipped and emptied, allowing the fruit it held and conveyed to leave the tunnel.
The height at which the fruit exits may be optionally chosen by adjusting the position of the flat tipping guide, which may move vertically along a C section, being fixed thereto at the desired position.
The top of the general prismatic rectangular box of the tunnel has conventional means for heating and forcing the flow of the drying air mass, and a motor driving the inner conveyor.
The drying tunnel designed with the above-mentioned structural, formal and functional characteristics provides a number of advantages over known tunnels travelling horizontally, for instance as follows:
a)xe2x80x94Less plan surface area is taken up, with the same length of travel of the fruit inside the tunnel, or even with a greater length.
b)xe2x80x94Total contact of the airflow with the fruit, sweeping its upper face in the upward sectors of the conveyor and its lower face through the bottom of the buckets in the downward sectors thereof, and consequently making operation more efficient.
c)xe2x80x94Adjustment of the height at which the fruit exits, fixing it as appropriate to facilitate the subsequent handling thereof.
d)xe2x80x94A rational replacement of air losses by optionally fitting a moisture control sensor which may, through electronic means, provide for the adjustment of the airflow entering from outside in order to be as strictly required to keep the physical constants at their optimum values.